Also, if you don't want to see calendars pop up, one of the phones will have to get these switched off from within the calendar setting. Then of course for her personal or your personal calendar you can sync another Outlook account or Gmail account with it's calendar.

I have two Microsoft accounts on my phone. I think you can have another account sync as well. I see the option for syncing content such as calendar, contacts, tasks and email. So maybe setup her account as secondary?